She can be found above the room of rats in the first area of the Valley of Defilement and in the second area of the world just past the entrance to the shanty town from the poison swamp.
Much like in the land of the blind, the man with one eye is King; in the land of the wretched and the diseased, a shrill harpy is desirable. Before Saint Astraea came to the Valley, the Filthy Woman was the most beautiful and desirable of all the females. After Saint Astraea and her knights came to the Valley, the outcasts paid little attention to her and that has shaped the Point-of-view of the Filthy Woman. She calls Astraea hateful names and believes that things were better before Astraea brought her "foulness" to the Valley. She sells the armor and weapons of all the Priests and Temple Knights in Astraea's entourage who were killed as well as the warriors of the Church who entered the Valley after the scourge to confirm the rumors that Saint Astraea had become a Demon.
The Filthy Woman will often attempt to guilt the player into purchasing items by mentioning her unseen, sick and hungry child. Her general demeanor, detectable bias about Astraea, and the fact that her child is never seen has lead many to believe that she is lying about having any children. Though Astraea came to the Valley on a mission of compassion, the Filth Woman claims she looked at her child with disgust. If this is truthful statement, it is likely that her child is one of the heretical shaman.